Storage for virtual environments, i.e., a so-called virtual storage apparatus, is conventionally known as a storage system capable of implementing a memory device having free volume configuration and memory capacity without restriction of volume configuration and memory capacity of a physical memory device. The virtual storage apparatus has within the apparatus a real storage apparatus controlling access to a physical memory device and creates a virtual volume by a processor managing the real storage apparatus.
The virtual volume is configured on processors in the virtual storage apparatus and is correlated with a physical memory area on the real storage apparatus. An agent present in each processor monitors an event such as control and error of a driver and notifies a manager. The manager is present in one processor in the virtual storage apparatus, manages configuration information and states of virtual volumes, and plays a role of controlling the agents.
The virtual storage apparatus mirrors, for example, a segment making up a virtual volume on the assumption that a failure occurs in the real storage apparatus storing data. The segment is an area of a constant size cut out from a logical unit number (LUN) of the real storage. The virtual storage apparatus continues access from the segment belonging to the LUN, at which a failure occurs, via a segment at a mirror destination assigned to belong to another LUN, thereby improving availability of storage.
Relevant prior art includes, for example, a technique of identifying a disk drive with a large repeat count of writing or reading of data out of multiple disk drives forming a logical memory area and blocking the identified disk drive. Also included is a technique of updating a counter in memory when a recoverable failure occurs and making an alarm notification to a manager if the count is equal to a threshold value. Alternatively, a failure occurrence frequency is calculated by hardware or software from failure information and date/time information recorded in an external memory device that records failure details and a failure occurrence time when a restorable failure occurs so as to determine whether an allowable value of the failure occurrence frequency has been exceeded. For examples of such techniques, refer to Japanese Laid-Open Patent Publication Nos. 2005-251042, H5-143377, and H6-103122.
However, conventional techniques have a problem of an increased period from the occurrence of an input/output error occurring in a real storage apparatus shared by multiple processors in a storage system until resumption of input/output via a mirror destination. For example, a process executed by a manager for the input/output error forms a bottleneck and therefore, a timeout time of an input/output request may be exceeded.